Craig Kundrot, deputy chief scientist of NASA's Human Research Program, says in a news release that the brothers provide a unique opportunity to study two people with the same genetics who were in different environments.

Officials say veteran astronaut Scott Kelly will embark on a year-long mission to the International Space Station in March 2015, while his identical twin brother, retired astronaut Mark Kelly, who will stay put on Earth, acting like an experimental control.

NASA says it is hoping the studies can be the basis for future research initiatives.